ebitmap.c

xen虚拟机源代码安装包

/*
 * Implementation of the extensible bitmap type.
 *
 * Author : Stephen Smalley, <[e-mail]>
 */

/* Ported to Xen 3.0, George Coker, <[e-mail]> */

#include <asm/byteorder.h>
#include <xen/lib.h>
#include <xen/xmalloc.h>
#include <xen/errno.h>
#include <xen/spinlock.h>
#include "ebitmap.h"
#include "policydb.h"

int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2)
{
    struct ebitmap_node *n1, *n2;

    if ( e1->highbit != e2->highbit )
        return 0;

    n1 = e1->node;
    n2 = e2->node;
    while ( n1 && n2 && (n1->startbit == n2->startbit) && (n1->map == n2->map) )
    {
        n1 = n1->next;
        n2 = n2->next;
    }

    if ( n1 || n2 )
        return 0;

    return 1;
}

int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
{
    struct ebitmap_node *n, *new, *prev;

    ebitmap_init(dst);
    n = src->node;
    prev = NULL;
    while ( n )
    {
        new = xmalloc(struct ebitmap_node);
        if ( !new )
        {
            ebitmap_destroy(dst);
            return -ENOMEM;
        }
        memset(new, 0, sizeof(*new));
        new->startbit = n->startbit;
        new->map = n->map;
        new->next = NULL;
        if ( prev )
            prev->next = new;
        else
            dst->node = new;
        prev = new;
        n = n->next;
    }

    dst->highbit = src->highbit;
    return 0;
}

int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2)
{
    struct ebitmap_node *n1, *n2;

    if ( e1->highbit < e2->highbit )
        return 0;

    n1 = e1->node;
    n2 = e2->node;
    while ( n1 && n2 && (n1->startbit <= n2->startbit) )
    {
        if ( n1->startbit < n2->startbit )
        {
            n1 = n1->next;
            continue;
        }
        if ( (n1->map & n2->map) != n2->map )
            return 0;

        n1 = n1->next;
        n2 = n2->next;
    }

    if ( n2 )
        return 0;

    return 1;
}

int ebitmap_get_bit(struct ebitmap *e, unsigned long bit)
{
    struct ebitmap_node *n;

    if ( e->highbit < bit )
        return 0;

    n = e->node;
    while ( n && (n->startbit <= bit) )
    {
        if ( (n->startbit + MAPSIZE) > bit )
        {
            if ( n->map & (MAPBIT << (bit - n->startbit)) )
                return 1;
            else
                return 0;
        }
        n = n->next;
    }

    return 0;
}

int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
{
    struct ebitmap_node *n, *prev, *new;

    prev = NULL;
    n = e->node;
    while ( n && n->startbit <= bit )
    {
        if ( (n->startbit + MAPSIZE) > bit )
        {
            if ( value )
            {
                n->map |= (MAPBIT << (bit - n->startbit));
            }
            else
            {
                n->map &= ~(MAPBIT << (bit - n->startbit));
                if ( !n->map )
                {
                    /* drop this node from the bitmap */

                    if ( !n->next )
                    {
                        /*
                         * this was the highest map
                         * within the bitmap
                         */
                        if ( prev )
                            e->highbit = prev->startbit + MAPSIZE;
                        else
                            e->highbit = 0;
                    }
                    if ( prev )
                        prev->next = n->next;
                    else
                        e->node = n->next;

                    xfree(n);
                }
            }
            return 0;
        }
        prev = n;
        n = n->next;
    }

    if ( !value )
        return 0;

    new = xmalloc(struct ebitmap_node);
    if ( !new )
        return -ENOMEM;
    memset(new, 0, sizeof(*new));

    new->startbit = bit & ~(MAPSIZE - 1);
    new->map = (MAPBIT << (bit - new->startbit));

    if ( !n )
        /* this node will be the highest map within the bitmap */
        e->highbit = new->startbit + MAPSIZE;

    if ( prev )
    {
        new->next = prev->next;
        prev->next = new;
    }
    else
    {
        new->next = e->node;
        e->node = new;
    }

    return 0;
}

void ebitmap_destroy(struct ebitmap *e)
{
    struct ebitmap_node *n, *temp;

    if ( !e )
        return;

    n = e->node;
    while ( n )
    {
        temp = n;
        n = n->next;
        xfree(temp);
    }

    e->highbit = 0;
    e->node = NULL;
    return;
}

int ebitmap_read(struct ebitmap *e, void *fp)
{
    int rc;
    struct ebitmap_node *n, *l;
    __le32 buf[3];
    u32 mapsize, count, i;
    __le64 map;

    ebitmap_init(e);

    rc = next_entry(buf, fp, sizeof buf);
    if ( rc < 0 )
        goto out;

    mapsize = le32_to_cpu(buf[0]);
    e->highbit = le32_to_cpu(buf[1]);
    count = le32_to_cpu(buf[2]);

    if ( mapsize != MAPSIZE )
    {
        printk(KERN_ERR "security: ebitmap: map size %u does not "
               "match my size %Zd (high bit was %d)\n", mapsize,
               MAPSIZE, e->highbit);
        goto bad;
    }
    if ( !e->highbit )
    {
        e->node = NULL;
        goto ok;
    }
    if ( e->highbit & (MAPSIZE - 1) )
    {
        printk(KERN_ERR "security: ebitmap: high bit (%d) is not a "
               "multiple of the map size (%Zd)\n", e->highbit, MAPSIZE);
        goto bad;
    }
    l = NULL;
    for ( i = 0; i < count; i++ )
    {
        rc = next_entry(buf, fp, sizeof(u32));
        if ( rc < 0 )
        {
            printk(KERN_ERR "security: ebitmap: truncated map\n");
            goto bad;
        }
        n = xmalloc(struct ebitmap_node);
        if ( !n )
        {
            printk(KERN_ERR "security: ebitmap: out of memory\n");
            rc = -ENOMEM;
            goto bad;
        }
        memset(n, 0, sizeof(*n));

        n->startbit = le32_to_cpu(buf[0]);

        if ( n->startbit & (MAPSIZE - 1) )
        {
            printk(KERN_ERR "security: ebitmap start bit (%d) is "
                   "not a multiple of the map size (%Zd)\n",
                   n->startbit, MAPSIZE);
            goto bad_free;
        }
        if ( n->startbit > (e->highbit - MAPSIZE) )
        {
            printk(KERN_ERR "security: ebitmap start bit (%d) is "
                   "beyond the end of the bitmap (%Zd)\n",
                   n->startbit, (e->highbit - MAPSIZE));
            goto bad_free;
        }
        rc = next_entry(&map, fp, sizeof(u64));
        if ( rc < 0 )
        {
            printk(KERN_ERR "security: ebitmap: truncated map\n");
            goto bad_free;
        }
        n->map = le64_to_cpu(map);

        if ( !n->map )
        {
            printk(KERN_ERR "security: ebitmap: null map in "
                   "ebitmap (startbit %d)\n", n->startbit);
            goto bad_free;
        }
        if ( l )
        {
            if ( n->startbit <= l->startbit )
            {
                printk(KERN_ERR "security: ebitmap: start "
                       "bit %d comes after start bit %d\n",
                       n->startbit, l->startbit);
                goto bad_free;
            }
            l->next = n;
        }
        else
            e->node = n;

        l = n;
    }

ok:
    rc = 0;
out:
    return rc;
bad_free:
    xfree(n);
bad:
    if ( !rc )
        rc = -EINVAL;
    ebitmap_destroy(e);
    goto out;
}